KR20010013529A - Polyalkylene naphthalate, composition thereof, film, and processes for producing these - Google Patents

Abstract

The present invention is a polyalkylene naphthalate having a naphthalenedicarboxylic acid component as a main dicarboxylic acid component and an aliphatic glycol component as a main glycol component, wherein the polyalkylene naphthalate comprises (a) an antimony compound and (b) A sulfonic acid quaternary phosphonium salt compound unit having an ester-forming functional group is a polyalkylene naphthalate for film, which is characterized by containing the following formulas (1) and (2), respectively.

0 <Sb ≤80 (1)

0 <S / Sb ≤0.4 (2)

(Wherein Sb and S are molar ratios of sulfonic acid quaternary phosphonium salt compound units each having an antimony compound and an ester-forming functional group per total dicarboxylic acid component forming a polyalkylene naphthalate (unit: mmol%)) Is displayed.)

The film of the present invention is excellent in surface flatness and is suitable for a base film for a magnetic recording medium. Moreover, it is excellent in high-speed cold property, and stable film forming is possible, and it can manufacture industrially advantageously.

Description

POLYALKYLENE NAPHTHALATE, COMPOSITION THEREOF, FILM, AND PROCESSES FOR PRODUCING THESE}

Polyalkylene naphthalates containing naphthalenedicarboxylic acid as the main dicarboxylic acid component and aliphatic glycol as the main glycol component, among them, polyethylene naphthalate has excellent physical and chemical properties, so it is used for fibers, films, resins, and the like. It is becoming. Among them, polyethylene naphthalate film is a film that is compatible with various properties such as strength, heat resistance and chemical resistance and cost, and is used as a base film for photographic films and magnetic tape films.

A polyethylene naphthalate film is formed into a film by the same method as polyester films, such as polyethylene terephthalate.

Typically, the polyester film is prepared by quenching the film-like polyester melt melt-extruded from the extrusion stopper on the surface of the rotary cooling drum, and then stretched in the horizontal and vertical directions. In this case, in order to eliminate the surface defects of the film and to increase the uniformity of the thickness, it is necessary to improve the adhesion between the melt-extruded film-like polyester and the surface of the rotary cooling drum. In this way, a wire-shaped metal electrode (hereinafter referred to as an electrostatic wire) is provided between the extrusion plug and the surface of the rotary cooling drum to deposit an electrostatic charge on the surface of the film-like melt (hereinafter referred to as the electrostatic cast method). Is known.

In film forming, increasing productivity and reducing manufacturing cost are important issues along with improvement of film quality, and therefore, it is the most effective method to increase the film forming speed by increasing the peripheral speed of the rotary cooling drum. However, when the circumferential speed of the rotary cooling drum is increased in the electrostatic cast method, the unit area electrostatic charge to the surface of the film-like material is reduced, thereby decreasing the adhesion to the rotary cooling drum and causing surface defects on the surface of the film. The problem that the film thickness becomes nonuniform arises. In order to increase the adhesion, a method of increasing the voltage applied to the electrode to increase the amount of static charge on the molten polyester may be employed. However, if the applied voltage is too high, an arc discharge occurs between the electrode and the rotary cooling drum, and the cooling drum The film-like material on the surface may break and damage the cooling drum surface. Therefore, it is virtually impossible to raise the voltage applied to the electrode to a certain degree or more.

Various methods have been proposed to overcome the limitations of the electrostatic cast method and to lower the specific resistance of molten polyester as a method of producing a polyester film with high efficiency by improving the film forming speed.

For example, the value of the alternating volume resistivity of a molten film containing sulfonic acid quaternary phosphonium salt having 0.1 to 45 mmol% of ester-forming functional groups in the polymer complex with respect to the dicarboxylic acid component forming the polyester is 6.5. A method of using polyester having a size of 10 ⁸ ? Cm or less (Japanese Patent Laid-Open No. 7-5675) and the like have been proposed.

In general, conventional catalysts are used in the production of polyesters, and especially antimony compounds have a high polymerization rate and are widely used because of excellent properties such as thermal stability, amount of terminal carboxyl groups, and softening point of polyesters obtained. However, antimony compounds are often precipitated in the manufacturing process of polymers and films, and it is known that the precipitated particles have a defect of forming small protrusions on the film surface (Japanese Patent Laid-Open No. 8-53541).

On the other hand, in the production of polyethylene naphthalate film, it is possible to suppress the occurrence of minute irregularities on the surface of the film by precipitation of catalyst components such as antimony compounds, to produce a film having excellent surface flatness, and also to provide excellent film film with excellent electrostatic adhesion. For the purpose of producing the same, a method of adding a specific amount of calcium compound, magnesium compound, phosphorus compound and antimony compound in polyethylene naphthalate in a specific ratio is described in Japanese Patent Application Laid-Open No. 8-104744.

However, it is also difficult to sufficiently prevent the presence of microprotrusions and the resulting obstacles due to the precipitation of the catalyst components even by the technique of selecting the catalyst component and optimizing the addition ratio thereof.

In the case of a film for a high density magnetic recording medium represented by a metal-deposited video tape requiring flatness and uniformity of the film surface, the presence of micro projections on the film surface is not preferable because it causes an error.

When the film formation rate was increased to increase the productivity during film formation of the polyalkylene naphthalate film, it was found that the precipitation of the antimony compound used as the catalyst affects the maximum winding speed during film formation.

Furthermore, it turned out that precipitation of the said antimony compound is related also to the film forming stability at the time of film forming.

In other words, by suppressing the formation of coarse particles due to the precipitation of antimony compounds and suppressing the size and number of the precipitates even when precipitated, it is possible to stably and industrially produce a homogeneous film while improving the maximum winding speed. It turned out to be possible.

The present invention relates to polyalkylene naphthalates, compositions thereof, films and methods for their preparation. More specifically, the present invention relates to a polyalkylene naphthalate containing a specific ratio of an antimony compound and a specific sulfonic acid quaternary phosphonium salt compound, a film made thereof, and a method for producing the same.

The present inventors believe that when a sulfonic acid quaternary phosphonium salt having an ester-forming functional group is added to produce a polyalkylene naphthalate film using an antimony compound as a catalyst, it is considered to be reduced antimony in the film compared to the concentration thereof. It was found that the micro precipitated particles increased.

Thus, when the film is produced by electrostatic casting with polyalkylene naphthalate obtained by optimizing the concentration of sulfonic acid quaternary phosphonium salt having an antimony compound and an ester-forming functional group and the ratio of both, adhesion to the rotary cooling drum It was found that this excellent, high-speed winding speed can be achieved and stable film production productivity can be obtained. In addition, the obtained film was excellent in the flatness and uniformity of the surface, it was found that the film is suitable for high-density magnetic recording media.

Means for Solving the Invention

This invention was achieved based on the said discovery, The polyalkylene naphthalate which makes a naphthalene dicarboxylic acid component a main dicarboxylic acid component, and makes an aliphatic glycol component a main glycol component, The said polyalkylene naphthalate, (a) an antimony compound and (b) a sulfonic acid quaternary phosphonium salt compound unit having an ester-forming functional group, respectively, in a proportion satisfying the following formulas (1) and (2): Phthalate.

0 <Sb ≤80 (1)

0 <S / Sb ≤0.4 (2)

(Wherein Sb and S are molar ratios of sulfonic acid quaternary phosphonium salt compound units each having an antimony compound and an ester-forming functional group per total dicarboxylic acid component forming a polyalkylene naphthalate (unit: mmol%)) Is displayed.)

Hereinafter, the present invention will be described in more detail.

Polyalkylene naphthalate in this invention is polyester formed using the naphthalenedicarboxylic acid component as a main dicarboxylic acid component, and the aliphatic glycol component as a main glycol component. By "main" here it is meant that at least 70 mol%, preferably at least 80 mol% or more of the total repeating units constituting the polyester are alkylene naphthalate units.

Such polyalkylene naphthalates are substantially linear and have excellent film formability, in particular film formation by melt molding.

As naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, etc. are suitable in the case of a direct esterification method, and when a polymer is manufactured by a transesterification method, Lower alkyl esters of these dicarboxylic acids can be used as raw materials.

Examples of these lower alkyl esters include dimethyl 2,6-naphthalenedicarboxylic acid, diethyl 2,6-naphthalenedicarboxylic acid, dimethyl 2,7-naphthalenedicarboxylic acid, and the like. Is dimethyl 2,6-naphthalenedicarboxylic acid which can be easily obtained industrially.

In the present invention, aliphatic glycols include alicyclic diols such as polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, or cyclohexanedimethanol. For example, ethylene glycol, propylene glycol, or 1,4-butanediol is preferable, and ethylene glycol is the most preferable.

In the polyester of the present invention, a copolymer obtained by copolymerizing a small amount of copolymerization components in a range in which the characteristics thereof are not impaired may be used.

The third component includes diols such as diethylene glycol, neopentyl glycol, polyalkylene glycol, and 1,4-cyclohexanedimethanol as the glycol component. Among them, diethylene glycol is preferable.

The preferable content of the diethylene glycol unit in the polyalkylene naphthalate is 0.4 to 3% by weight, particularly preferably 0.8 to 2% by weight. When the content of the diethylene glycol unit is less than 0.4% by weight, the crystallization of the polymer is not suppressed and the melting energy is increased. Therefore, the unmelted polymer remains during the film formation, which is not preferable because coarse protrusions are formed on the film surface. On the other hand, when it exceeds 3 weight%, since the strength after film formation, for example, Young's modulus falls and durability falls, it is unpreferable.

Further, in the polyalkylene naphthalate of the present invention, as the dicarboxylic acid component of the third component, dicarboxylic acids such as terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid and phthalic acid, and ester formability thereof. And polyfunctional polycarboxylic acids such as derivatives, trimellitic acid and pyromellitic acid, and ester ester derivatives thereof. Preferred among these are terephthalic acid, isophthalic acid and these ester-forming derivatives (for example, dimethyl terephthalate and dimethyl isophthalate). It is preferable to set the terephthalic acid component and the isophthalic acid component to 20 mol% or less of the total dicarboxylic acid component because it does not impair the effect of the present invention. Especially preferred is 10 mol% or less.

The polyalkylene naphthalate of the present invention may be used in oxycarboxylic acid components such as, for example, aromatic oxyacid components such as hydroxybenzoic acid and aliphatic oxyacids such as ω-hydroxycapronic acid, so long as the object of the present invention is not impaired. The derived component may be contained.

The polyalkylene naphthalate of the present invention is particularly advantageous that at least 80 mol%, preferably at least 90 mol% of the total repeating units thereof is ethylene-2,6-naphthalate or ethylene-2,7-naphthalate.

Moreover, in the polyalkylene naphthalate of this invention, additives, such as a light stabilizer, antioxidant, and a light-shielding agent, can be contained as needed in the range which does not impair physical properties, such as surface flatness and dry heat deterioration property.

The polyalkylene naphthalate of the present invention can be produced by a method known per se. As a preferable manufacturing method, for example, ester-forming derivatives and aliphatic glycols of naphthalenedicarboxylic acid are heated in the presence of a transesterification catalyst to perform transesterification, followed by polycondensation in the presence of a polycondensation catalyst. There is a way.

As said polyester, it is preferable that the intrinsic viscosity measured and calculated | required at 35 degreeC with the solution in o-chlorophenol is 0.4-0.9, and it is especially preferable that it is 0.45-0.75 (unless specifically indicated below, intrinsic viscosity is o It is a value obtained by measuring at 35 ° C. with a solution in chlorophenol).

The amount of antimony compound as catalyst in the polyalkylene naphthalate of the present invention needs to satisfy the following formula (1).

0 <Sb ≤80 (1)

(In the above formula, Sb represents the molar ratio of the total dicarboxylic acid component of the antimony compound, and the unit is mmol%.) The more preferable amount of the antimony compound is an amount that satisfies the following formula (1 ').

5 ≤ Sb ≤70 (1 ')

Particularly preferred Sb amount is in the range of 10 to 60 mmol%. When this amount exceeds 80 mmol%, black foreign matters originating in antimony tend to occur, and the surface flatness of the film deteriorates, which is not preferable. If the amount of Sb is too small, it is not preferable because the polymerization reaction does not proceed.

The antimony compound that can be used in the present invention is not particularly limited, and examples thereof include antimony trioxide, antimony pentoxide, and the like. Among them, antimony trioxide is particularly preferable.

In the present invention, the antimony compound may be added at any stage, such as before the start of the transesterification reaction, during the transesterification reaction, after the end of the transesterification reaction, or just before the polycondensation reaction.

In the present invention, the sulfonic acid quaternary phosphonium salt having an ester-forming functional group needs to satisfy the following formula (2).

0 <S / Sb ≤0.4 (2)

(Wherein Sb and S each represent a molar ratio of the sulfonic acid quaternary phosphonium salt component having an antimony compound and an ester-forming functional group per total dicarboxylic acid component forming a polyalkylene naphthalate, wherein the unit is mmol%) to be.)

More preferable ratio of S / Sb is the range which satisfy | fills following formula (2 ').

0.001 ≤ S / Sb ≤0.3 (2 ')

The most preferable ratio of S / Sb is in the range of 0.01 to 0.2.

When the S / Sb ratio is more than 0.4, black foreign matters caused by antimony tend to occur, and the surface flatness of the film deteriorates, which is not preferable. In addition, in the case of 0, when there is no sulfonic acid quaternary phosphonium salt having an ester-forming functional group, electrostatic adhesion deteriorates and film forming productivity deteriorates.

As a sulfonic acid quaternary phosphonium salt which has an ester forming functional group which can be used by this invention, the compound represented by a following formula is mentioned, for example.

(Wherein A is a group containing an aromatic ring having 6 to 18 carbon atoms, Y ₁ and Y ₂ are the same or different, a hydrogen atom or an ester-forming functional group, provided that Y ₁ and Y ₂ are hydrogen atoms simultaneously) N is 1 or 2, and R <_1> , R <_2> , R <_3> and R <_4> are the same or different, and are a C1-C18 alkyl group, a benzyl group, or a C6-C12 aryl group. )

In the formula, A is a group containing an aromatic ring having 6 to 18 carbon atoms, for example, a group containing a benzene skeleton, a naphthalene skeleton or a biphenyl skeleton is preferable. In addition to the Y ₁ , Y _2, and sulfonic acid quaternary phosphonium bases, such aromatic rings may be substituted with aromatic hydrocarbons by, for example, an alkyl group having 1 to 12 carbon atoms.

Y ₁ and Y ₂ are hydrogen atoms or ester-forming functional groups, but they are not hydrogen atoms at the same time. The ester-forming functional groups are, for example, -COOH, -COOR ', -OCOR',-(CH ₂ ) _m OH ,-(OCH ₂ ) _m OH and the like. Of these groups, R 'is a lower alkyl group or phenyl group having 1 to 4 carbon atoms, m is an integer of 1 to 10, and R' is preferably methyl, ethyl, n-propyl, iso-propyl or n-butyl. Can be.

In addition, R ₁ , R ₂ , R ₃ and R ₄ constituting the base portion (P ⁺ R ₁ R ₂ R ₃ R ₄ ) of the sulfonic acid quaternary phosphonium salt may be the same or different, and have an alkyl group having 1 to 18 carbon atoms. , A benzyl group or a C6-C12 aryl group, and examples of the C1-C18 alkyl group include methyl, ethyl, propyl, butyl, dodecyl, stearyl and the like. Moreover, as a C6-C12 aryl group, phenyl, naphthyl, biphenyl, etc. are mentioned, for example. As a preferable specific example of the said sulfonic acid quaternary phosphonium salt, 3, 5- dicarboxy benzene sulfonic acid tetrabutyl phosphonium salt, 3, 5- dicarboxy benzene sulfonic acid ethyl tributyl phosphonium salt, 3, 5- dicarboxy benzene sulfonic acid Benzyl tributyl phosphonium salt, 3, 5- dicarboxy benzene sulfonate phenyl tributyl phosphonium salt, 3, 5- dicarboxy benzene sulfonate tetraphenyl phosphonium salt, 3, 5- dicarboxy benzene sulfonate butyl triphenyl phosphonium salt , 3,5-dicarbomethoxybenzenesulfonate tetrabutylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonate ethyl tributylphosphonium salt, 3,5-dicarbomethoxybenzenesulfonate benzyl tributylphosphonium salt , 3,5-dicarbomethoxybenzenesulfonate phenyltributylphosphonium salt, 3,5-di (β-hydroxyethoxycarbonyl) benzenesulfonate tetrabutylphosphonium salt, 3,5-di (β-hydride Roxyethoxycarbonyl) benzene sulfonic acid tetraphenyl phosphonium salt, 3-dicarboxy benzene sulfonic acid tetra Butyl phosphonium salt, 3-dicarboxy benzene sulfonic acid tetraphenyl phosphonium salt, 3-di ((beta) -hydroxyethoxycarbonyl) benzene sulfonic acid tetra butyl phosphonium salt, 3-di ((beta-hydroxyethoxycarbonyl) ) Benzenesulfonic acid tetraphenylphosphonium salt, 4-di ((beta-hydroxyethoxycarbonyl) benzenesulfonic acid tetrabutylphosphonium salt, bisphenol A-3,3-di (sulfonic acid tetrabutylphosphonium salt), 2,6 -Dicarboxy naphthalene-4-sulfonic acid tetrabutyl phosphonium salt, etc. are mentioned. The said sulfonic acid quaternary phosphonium salt may be used individually by 1 type, and may use two or more types together.

In the polyalkylene naphthalate of the present invention, it is preferable to contain the sulfonic acid quaternary phosphonium salt in the polyalkylene naphthalate so that the AC volume resistivity at the time of melting becomes 2.0x10 <^8> ohm cm or less. Polyalkylene naphthalate having an AC volume resistivity of 2.0 × 10 ⁸ Ωcm or less at the time of melting can provide sufficient charge amount to adhere even on a relatively fast rotating cooling drum, thereby achieving an improvement in the film forming speed, which is one of the objects of the present invention. can do.

In the present invention, the sulfonic acid quaternary phosphonium salt may be contained in the polyalkylene naphthalate main chain or at the terminal, that is, copolymerized, or simply mixed in the polymer. In any state, the improvement of the film forming speed can be achieved.

In the present invention, the polyalkylene naphthalate preferably has an AC volume resistivity value in the range of 2.0 × 10 ⁸ to 6.0 × 10 ⁶ Ωcm at the time of melting.

In the present invention, as the method of containing the sulfonic acid quaternary phosphonium salt having an ester-forming functional group in the polyalkylene naphthalate, it can be added at any stage until the synthesis of the aforementioned polyalkylene naphthalate is completed. . It is preferable to add before starting polycondensation reaction in superposition | polymerization of polyalkylene naphthalate.

In addition, polyalkylene naphthalate containing a sulfonic acid quaternary phosphonium salt having an ester-forming functional group at a higher concentration than the above ratio is produced once, and polyalkyl which does not contain a sulfonic acid quaternary phosphonium salt component in the production step of the film. After blending with rennaphthalate and adjusting it to a predetermined content, a method of film melt molding may be employed.

According to the study of the present inventors, it is preferable that the said polyalkylene naphthalate of this invention contains a calcium compound, a magnesium compound, and a phosphorus compound at the ratio which satisfy | fills following formula (3)-(5) simultaneously. Able to know.

10 ≤ (Mg + Ca) ≤120 (3)

0.5 ≤Mg / Ca ≤10 (4)

0.5 ≤ (Mg + Ca) / P ≤8.0 (5)

(In the above formula, Mg, Ca and P each contain a sulfonic acid quaternary phosphonium salt compound unit having a magnesium compound, a calcium compound and an ester-forming functional group per all dicarboxylic acid components forming a polyalkylene naphthalate). Molar ratio of the total phosphorus compound (unit is mmol%).)

The preferable addition ratio of a calcium compound, a magnesium compound, and a phosphorus compound is a ratio which satisfy | fills following formula (3 '), (4'), and (5 ').

20 ≤ (Mg + Ca) ≤ 110 (3 ')

0.5 ≤Mg / Ca ≤9 (4 ')

1 ≤ (Mg + Ca) / P ≤ 7 (5 ')

(In the above formula, Mg, Ca and P have the same meaning as the definitions in the formulas (3), (4) and (5).)

As the calcium compound and magnesium compound which can be used in the present invention, oxides, chlorides, carbonates and carboxylates of Ca and Mg are preferable, and acetates, that is, calcium acetate and magnesium acetate are particularly preferable.

In the present invention, the addition time of the calcium compound and the magnesium compound may be added at any stage of the polyester production process.

The calcium compound and the magnesium compound have an effect of lowering the resistance ratio during melting of the polymer in the polyalkylene naphthalate of the present invention, but employ a transesterification reaction using dimethyl naphthalenedicarboxylic acid and aliphatic glycol in the production step. In this case, it can also be used as a transesterification catalyst.

Therefore, when using also as a transesterification catalyst, it adds before starting transesterification reaction.

Although there is no particular limitation as long as it does not need to function as a transesterification catalyst, the addition time of the calcium compound and the magnesium compound is preferably performed until the intrinsic viscosity of the reaction polymer reaches 0.2 so that the compound can be easily dispersed in the polymer. An example of the method is available. In addition, the addition order may add both compounds simultaneously or may add each time.

In the present invention, the addition amount of the calcium compound and the magnesium compound is, for example, when polyalkylene naphthalate is obtained by a transesterification method, the total content of calcium and magnesium (Mg + Ca) is 10 to 120 with respect to all the dicarboxylic acid components. Magnesium compounds and calcium compounds which are soluble in the reaction system are added as a transesterification catalyst so as to be mmol%, preferably 20 to 110 mmol%, particularly preferably 30 to 100 mmol%. The mmol% below represents the amount in mmol% of each element with respect to the total dicarboxylic acid component.

If the amount exceeds 120 mmol%, the surface flatness of the film is deteriorated due to the effect of precipitated particles due to catalyst residues, which is not preferable. On the other hand, if the amount is less than 10 mmol%, not only the transesterification reaction is insufficient, but also the subsequent polymerization. The reaction is also delayed, which is undesirable.

Moreover, the molar ratio (Mg / Ca) of magnesium with respect to calcium is 0.5-10, and 0.5-9.0 are preferable. Especially preferably, it is 2.0-8.0. If the ratio is 0.5 or less, surface flatness deteriorates when molded into a film under the influence of precipitated particles due to catalyst residues.

When it exceeds 10, the various characteristics at the time of using a film deteriorate, and it is not preferable.

In addition, a phosphorus compound is added to deactivate a portion of the transesterification catalyst, but the amount of transesterification catalyst, i.e., calcium and magnesium addition amount, to the total amount of phosphorus element including sulfonic acid quaternary phosphonium salt having an ester-forming functional group is added. In other words, the total molar ratio (Mg + Ca) / P is in the range of 0.5 to 8.0, with 1.0 to 7.0 being preferred. 2.0-7.0 are especially preferable.

If the ratio of the added amount exceeds 8, the surface flatness deteriorates when it is formed on the film under the influence of precipitated particles due to catalyst residues. On the other hand, when the ratio is less than 0.5, the polymerization catalyst is caused by the excess phosphorus compound for the transesterification catalyst. It is not preferable because the antimony compound is inactivated, the polymerization reaction is substantially long, and the productivity is lowered.

In the present invention, the addition time of the phosphorus compound is preferably added after the transesterification reaction or the esterification reaction is substantially completed. In addition, it can also add in batch or divided | segmented into 2 or more times.

As the phosphorus compound which can be used in the present invention, trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, phosphoric acid and the like are preferable. More preferred is trimethyl phosphate.

In addition, in the present invention, a trace amount of another metal compound may be included in the range that does not interfere with the object of the present invention, and for example, may include metal compounds such as Zn, Co, Mn, K, Na, and the like.

The modified polyalkylene naphthalate obtained in the present invention is particularly useful as a raw material for forming a film for a high density magnetic recording medium having little or no polymer insoluble matter resulting from the catalyst and having excellent film forming properties.

As a means for molding the modified polyalkylene naphthalate of the present invention into a film, a known method can be used. For example, the dried polyalkylene naphthalate is melt-extruded onto a sheet in the temperature range of [Tm]-[Tm + 65] ° C (Tm is the melting point ° C of polyalkylene naphthalate), rapidly cooled and unstretched film ( Sheet). Subsequently, the unstretched film is stretched in the vertical direction, and then stretched in the horizontal direction. Stretching is carried out by a so-called vertical and horizontal difference biaxial stretching method or a method of stretching in reverse order. The stretching temperature, the stretching ratio, and the like can be selected from means and conditions known per se.

According to the present invention, since a film having excellent surface flatness can be obtained and its electrostatic adhesion is good, it is easy to mold the film, can be molded at a high winding speed, and a high productivity polyalkylene naphthalate can be obtained.

The inventors of the present invention have further studied the film production from the polyalkylene naphthalate of the present invention, when the film is made of a composition in which the inert particles of a specific shape uniformly dispersed in the polymer, the surface flatness and the surface of the It has been found that the homogeneity is not impaired at all, and furthermore, the slipperiness and running durability of the film are further improved.

Thus, according to this invention, the polyalkylene naphthalate which makes a naphthalene dicarboxylic acid component the main dicarboxylic acid component, and makes an aliphatic glycol component the main glycol component, The said polyalkylene naphthalate is (a) antimony compound And (b) a sulfonic acid quaternary phosphonium salt compound unit having an ester-forming functional group in a proportion satisfying the following formulas (1) and (2), respectively, and containing inert fine particles having an average particle diameter of 0.01 to 0.5 µm. There is provided a polyalkylene naphthalate composition for a film, characterized in that.

0 <Sb ≤80 (1)

0 <S / Sb ≤0.4 (2)

(Wherein Sb and S are molar ratios of sulfonic acid quaternary phosphonium salt compound units each having an antimony compound and an ester-forming functional group per total dicarboxylic acid component forming a polyalkylene naphthalate (unit: mmol%)) Indicates.)

In the polyalkylene naphthalate composition, since the polyalkylene naphthalate has already been described in detail with respect to the types and ratios of polymer components, antimony compounds, sulfonic acid quaternary phosphonium salts, magnesium compounds, calcium compounds and phosphorus compounds, In the description of the description thereof will be omitted. Hereinafter, the inert fine particles will be described in detail.

The inert fine particles used in the composition of the present invention need to have an average particle diameter of 0.01 to 0.5 µm. More preferably, it is 0.03-0.4 micrometer. If the average particle diameter is less than 0.01 µm, the slip resistance and wear resistance when the film is formed are insufficient. In addition, when the average particle diameter exceeds 0.5 mu m, the surface roughness is so large that the film flatness is impaired, so that the flatness required for the base film of the high density recording magnetic medium cannot be obtained.

At this time, only one type of inert fine particles may be used, or two or more types may be used. When using two or more types, different types of inert fine particles may be used, particles having different particle diameters may be used, or inert fine particles having different types and particle sizes may be used in combination.

The polyalkylene naphthalate composition in this invention contains the inert particle of the said shape. Examples of the inert fine particles that can be used herein include inorganic fine particles such as silica, titania, alumina, zirconia, kaolinite, and talc, or organic fine particles of crosslinked polymers such as crosslinked polystyrene, crosslinked acrylic, and crosslinked polyester. Among these, inert inorganic fine particles, silica particles, titania particles or alumina particles having a hydroxyl group having a polymer affinity on the surface thereof are preferable.

Although there is no restriction | limiting in particle shape etc. with respect to these particles, In order to make a film surface more flat and uniform, it is more preferable to use monodisperse spherical inorganic fine particles.

In addition, when using monodisperse spherical inorganic fine particles, it is preferable to define by following formula (6) and to have a volume spherical coefficient (phi) in the range of 0.30-(pi) / 6. This range means that the shape of the fine particles is spherical or close to the shape.

φ = V / d ³ (6)

(V here means an average volume (μm ³ ) calculated from an average particle diameter determined by the measuring method described below, and d means an average diameter (μm) of the maximum diameter on the projection surface.)

V can be easily calculated from the average particle diameter. In addition, d degree particles can be easily obtained by observing, photographing, and analyzing images with a scanning electron microscope.

In addition, it is preferable that the monodisperse spherical inorganic fine particles have a pore volume of 1.0 ml / g or less. When the pore volume exceeds 1.0 ml / g, the particles tend to be pulverized, which is not preferable because the pulverization in the film forming step, the running durability when the product is made, and the like deteriorate.

In addition, it is preferable that the monodisperse spherical inorganic fine particles have a specific surface area of 100 m ² / g or less. When the specific surface area exceeds 100 m ² / g, the interparticle interaction increases, so that the intergranular aggregation easily occurs, and the particle dispersibility deteriorates.

In the present invention, the use of spherical silica particles in which the particle size, shape, pore volume and specific surface area satisfy the above-mentioned conditions is particularly effective.

In the present invention, the addition amount of the inert particulates to the polyalkylene naphthalate is 0.01 to 10% by weight, preferably 0.01 to 5% by weight, particularly preferably 0.02 to 1% by weight. If the amount exceeds 10% by weight, sufficient dispersibility may not be obtained. On the contrary, when it is less than 0.01 weight%, the effect of particle addition is not fully expressed.

In addition, the inert fine particles in the obtained polyalkylene naphthalate composition are uniformly dispersed. Therefore, when the polyalkylene naphthalate is a stretched film, the particles in the film are less pulverized and a uniform uneven surface can be obtained. It is possible to obtain a film excellent in corrosion resistance and wear resistance.

The polyalkylene naphthalate obtained in the present invention is excellent in film forming properties with little or no amount of polymer insolubles due to the catalyst, and is particularly useful as a raw material for forming a base film of a high density magnetic recording medium.

Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example, unless the summary is exceeded. In addition, the measuring method and definition of various physical properties and characteristics in the Example are as follows.

(1) flatness

An aluminum spatter is applied to the surface of a small piece of film, and a range of 3 mm x 3 mm is observed at a magnification of 200 times while irradiating differential light with an optical microscope. Then, the flatness of the film is evaluated by counting the projections and the recognizable particles due to antimony precipitation. At this time, the projection by the inert fine particles is subtracted from the count number. That is, the count of the protrusion in the case of containing inert fine particles is the value calculated | required according to the following method.

Count and count protrusions and recognizable particles.

Thereafter, aluminum on the surface of the film is removed with an aqueous sodium hydroxide solution, and the surface of the film is ion-etched stepwise by a sputtering device (1B-2 type ion coater device) manufactured by Aiko Engineering Co., Ltd. After each step, carbon deposition was carried out and the particles marked with a scanning electron microscope were observed to determine what particles the inert particles are involved in. Then, the particles of the inert fine particles (for example, agglomerated particles of the inert particles) were identified. In this case, flatness is evaluated from the count value to the limit value.

〈4-step measurement〉

◎ No. of projections 20 / mm ² or less

○ number of protrusions 21-40 / mm ²

X number of protrusions 40-99 / mm ²

X × number of projections 100 / mm ² or more

(2) precipitated particles in the polymer

When a polyester film has a magnetic layer, an in-line coating layer, etc., it removes them with strong alkaline water, an organic solvent, etc., and wash | cleans with distilled water, and it dries. Even in the absence of a magnetic layer, it is sufficiently washed with distilled water and dried by removing the surface deposits.

100g of polyester films are extract | collected, 1 kg of o-chlorophenols are added, it heats up to 120-140 degreeC, stirring, and melts polyester, maintaining for about 3 to 5 hours. However, when the crystallization part etc. are not melt | dissolved, the once-warmed o-chlorophenol is quenched and the said dissolution operation is performed again.

Subsequently, in order to remove the foreign material etc. which are contained in polyester, the above-mentioned o-chlorophenol dissolution liquid is filtered by G-1 glass filter, and this residue weight is subtracted from a sample weight.

The G-1 glass filter filtrate was treated for one hour at 30,000 rpm using a Hitachi Seisakusho ultracentrifuge (55P-7 type, rotor type RP-30-2) to centrifuge the fine particles in the o-chlorophenol solution. Separation is performed. Particle sedimentation was confirmed by measuring the light transmittance of the o-chlorophenol solution before and after centrifugation, and after the separation, the value of the light transmittance of 375 μm was higher or equal to that before the separation. Check it. After centrifugation, the supernatant is removed by decantation and the separated particles are taken out. Since the separated particles may contain a polyester component due to insufficient centrifugation, o-chlorophenol at room temperature is added to the separated particles, and the dispersed particles are uniformly dispersed with an ultrasonic disperser, and then again. The ultracentrifugation process is performed. This operation needs to be repeated until the reprecipitation of the polyester component is not seen when excessively added to an organic solvent such as methanol in the supernatant.

The separated particles (A) separated by the above-mentioned method is vacuum dried at 100 ° C. for 8 hours to measure the amount. The separated particles obtained here are precipitated particles derived from catalytic metal elements.

(3) electrostatic adhesion

When the polymer is dried at 180 ° C. and melt-extruded at 305 ° C. and rapidly cooled on a casting drum maintained at 40 ° C. to wind the unstretched film, the film is wound at a stable winding speed with little thickness unevenness by the electrostatic peening method. Electrostatic adhesiveness is evaluated.

○: winding speed 40 m / min or more

(Triangle | delta): Winding speed 30 m / min or more and less than 40 m / min

X: less than 30 m / min winding speed

(4) dispersibility

A small piece of sample film is fixed to a sample stand for scanning electron microscope, and ion etching treatment is performed on the surface of the film by using a sputtering device (1B-2 type ion coater device) manufactured by Aiko Engineering Co., Ltd. under the following conditions.

Under the conditions, a sample was placed in a cylinder jar, the degree of vacuum was increased to a vacuum state of about 5 x 10 ^-2 Torr, and ion etching was performed for about 5 minutes at a voltage of 0.90 kV and a current of 5 mA. In addition, gold sputtering was performed on the surface of the film by the same apparatus, and the aggregation state of the particles was observed and evaluated by observing the range of 5 µm x 10 µm at 5000 times using a scanning electron microscope.

○ Less than 15% of all particles in the measurement area exist as aggregated particles

△ 15% to less than 30% of all particles in the measurement area exist as aggregated particles

× At least 30% of all particles in the measured area exist as aggregated particles

(5) Average particle size of particles

The particle size is measured by the following method.

Water was added to the dispersion liquid in which the inert inorganic particles were dispersed in the medium to obtain a low concentration solution, and then the average particle diameter was measured using a centrifugal sedimentation particle size distribution analyzer (CAPA-500) manufactured by Shimadzu Corporation.

(6) Film production stability

The film production stability is evaluated by evaluating the thickness nonuniformity when the film is produced at a winding speed of 50 m / min. That is, the obtained film is cut out in 2 m of sample film pieces in the width direction, the thickness is measured by an electron micrometer manufactured by Anritsu, the thickness change and the average value are obtained, and the film production stability is shown by the following three steps of evaluation.

<Three phases of evaluation>

◎ The difference between average thickness and maximum or minimum thickness is less than 0.3 ㎛

○ The difference between average thickness and maximum or minimum thickness is 0.3 µm or more and less than 0.5 µm

× difference between average and maximum or minimum thickness

Example 1

100 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester, 60 parts of ethylene glycol, 0.045 parts of magnesium acetate 4 beard, and 0.009 parts of calcium acetate 1 beard are used as a transesterification catalyst, and the content of diethylene glycol in the polymer The amount to become 0.7 wt% is added.

After transesterification according to a conventional method, 0.011 part of trimethyl phosphate is added to substantially terminate the transesterification reaction.

Then a mixture of 0.023 parts of antimony trioxide and 0.002 parts of 3,5-dicarboxybenzenesulfonate tetrabutylphosphonium salt is added. Thereafter, the mixture is transferred to a polymerization reactor, the temperature is raised to 295 ° C., and a polycondensation reaction is carried out by a conventional method under a vacuum degree of 26.7 Pa or less to obtain a modified polyethylene naphthalate having an intrinsic viscosity of 0.61. The altered volume resistivity value at 290 ° C. of this modified polyethylene naphthalate was 3.1 × 10 ⁷ Ωcm.

The modified polyethylene naphthalate pellets were dried at 170 ° C. for 3 hours, fed into an extruder hopper, passed through a 1 mm slit band at a melting temperature of 290 ° C., and melt-extruded at 200 μm, followed by surface finishing using a linear electrode. About 0.3 second, it solidifies on a rotary cooling drum of surface temperature of 20 degreeC. At this time, the casting speed is 50 m / min to increase the speed of the cooling drum slowly and stably produce the cooling film without causing surface defects of the film due to poor adhesion. Subsequently, the unstretched film was preheated at 75 ° C., stretched 3.6 times by heating with a IR heater having a surface temperature of 900 ° C. from 15 mm above between low-speed and high-speed rolls, and fed to a stenter, and then horizontally at 105 ° C. 3.9 times in the direction of stretching. The obtained biaxially oriented film was subjected to heat setting treatment at a temperature of 230 ° C. for 5 seconds to obtain a modified polyethylene naphthalate film having a heat setting biaxial stretching of 14 μm in thickness.

The characteristics of this film are shown in Table 1 and Table 2.

Example 2

120 parts of bis-β-hydroxyethyl ester of 2,6-naphthalenedicarboxylic acid and 85 parts of 2,6-naphthalenedicarboxylic acid and 30 parts of ethylene glycol and 3,5-dicarboxybenzene sulfonic acid tetrabutyl phospho A mixture of 0.01 part of the salt of nium is added, and diethylene glycol is added so that the content in the polymer is 1.0 wt%, and the ester reaction is performed at a temperature of 210 to 230 ° C.

The reaction was terminated when the amount of water produced by the reaction was 13 parts added, and 0.045 parts of magnesium acetate 4 beard, 0.009 parts of calcium acetate 1 and 0.02 parts of trimethyl phosphate were added and stirred for 10 minutes, and then 0.046 parts of antimony trioxide was added. Thereafter, the reaction product is transferred to a polymerization reactor, and the temperature is raised to 295 ° C. to carry out a polycondensation reaction under a high vacuum of 26.7 Pa or less to obtain a modified polyethylene naphthalate having an intrinsic viscosity of 0.61. The alternating volume resistivity value at 290 ° C. of this modified polyethylene naphthalate was 3.1 × 10 ⁷ Ωm. The obtained modified polyethylene naphthalate is formed into a film in the same manner as in Example 1 to obtain a modified polyethylene naphthalate film.

As shown in Table 1 and Table 2, the characteristics of this film are those having few precipitated particles and excellent film flatness and electrostatic adhesion.

Example 3

Modified polyethylene in the same manner as in Example 1, except that 100 parts of dimethyl 2,6-naphthalenedicarboxylic acid was substituted with 91 parts of dimethyl 2,6-naphthalenedicarboxylic acid and 9 parts of dimethyl isophthalate. Obtain a naphthalate film. As shown in Table 1 and Table 2, the characteristics of this film were low in precipitated particles and excellent in flatness and electrostatic adhesion of the film.

Examples 4-6

Example 1, except that the amount of 3,5-dicarboxybenzenesulfonate tetrabutylphosphonium salt, magnesium acetate, calcium acetate, trimethyl phosphate and antimony trioxide was changed to the amount shown in Table 1 and In the same manner, a modified polyethylene naphthalate film is obtained. As shown in Table 1 and Table 2, the characteristics of this film are that they have few precipitated particles and are excellent in flatness and electrostatic adhesion of the film.

Example 7

In Example 3, a modified polyethylene naphthalate film is obtained in the same manner as in Example 3 except that the amount of isophthalic acid is changed to the amount shown in Table 1. As shown in Table 1 and Table 2, the characteristics of this film are that they have few precipitated particles and are excellent in flatness and electrostatic adhesion of the film.

Example 8

In Example 3, a modified polyethylene naphthalate film is obtained in the same manner as in Example 3, except that acid components other than naphthalenedicarboxylic acid are changed to the acid components and amounts shown in Table 1. As shown in Table 1 and Table 2, the characteristics of this film are that they have few precipitated particles and are excellent in flatness and electrostatic adhesion of the film.

Comparative Examples 1 to 4

Example 1, except that the amounts of 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt, magnesium acetate, trimethyl phosphate, diethylene glycol and antimony trioxide were changed to the amounts shown in Table 1 In the same manner as in the modified polyethylene naphthalate film is obtained. As shown in Tables 1 and 2, the properties of this film are poor in flatness and inferior in precipitated particles as compared with Examples.

Example 9

100 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester, 60 parts of ethylene glycol, 0.045 parts of magnesium acetate 4 beard and 0.009 parts of calcium acetate 1 are used as a transesterification catalyst, and diethylene glycol is used in the polymer The amount which content becomes 0.7 wt% is added.

The transesterification is carried out according to a conventional method, and then 0.011 parts of trimethyl phosphate is added to substantially terminate the transesterification reaction.

Then a mixture of 0.023 parts of antimony trioxide and 0.002 parts of 3,5-dicarboxybenzenesulfonate tetrabutylphosphonium salt is added. Further, spherical silica having an average particle diameter of 0.06 mu m is added so that the concentration in the polymer is 0.05 wt%. Thereafter, the mixture is transferred to a polymerization reactor, the temperature is raised to 295 ° C, and a polycondensation reaction is carried out by a conventional method under a high vacuum of 26.7 Pa or less to obtain a polyethylene naphthalate composition having an intrinsic viscosity of 0.61. The AC volume resistivity value at 290 ° C. of this polyethylene naphthalate composition was 3.1 × 10 ⁷ Ωcm.

The polyethylene naphthalate pellet was dried at 170 ° C. for 3 hours, then fed to an extruder hopper, passed through a 1 mm slit band at a melting temperature of 290 ° C. and melt-extruded at 200 μm, and then surface finished using a linear electrode. About 0.3 second, it solidifies on a rotary cooling drum of surface temperature of 20 degreeC. At this time, the casting speed is 50 m / min to increase the speed of the cooling drum slowly and stably produce the cooling film without causing surface defects of the film due to poor adhesion. Subsequently, the unstretched film was preheated at 75 ° C., stretched 3.9 times by heating with a IR heater having a surface temperature of 900 ° C. from 15 mm above between low-speed and high-speed rolls, and then fed to a stenter and horizontally at 105 ° C. 3.9 times in the direction of stretching. The obtained biaxially oriented film was heat-set for 5 seconds at a temperature of 230 ° C. to obtain a heat-fixed biaxially oriented film having a thickness of 14 μm.

The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Example 10

120 parts of bis-β-hydroxyethyl ester of 2,6-naphthalenedicarboxylic acid and 85 parts of 2,6-naphthalenedicarboxylic acid and 30 parts of ethylene glycol and 3,5-dicarboxybenzene sulfonic acid tetrabutyl phospho A mixture of 0.01 part of the salt of nium is added, and the content of diethylene glycol is added so as to be 1.0 wt%, and the esterification reaction is performed at a temperature of 210 to 230 ° C.

The reaction was terminated when the amount of water produced by the reaction was added to 13, and 0.045 parts of magnesium acetate 4 beard, 0.009 parts of calcium acetate 1 and 0.02 parts of trimethyl phosphate were added, stirred for 10 minutes, and then 0.046 parts of antimony trioxide was added. Further, spherical silica having an average particle diameter of 0.06 mu m is added so that the concentration in the polymer is 0.05 wt%. Thereafter, the reaction product is transferred to a polymerization reactor, the temperature is raised to 295 ° C, and a polycondensation reaction is carried out under a high vacuum of 26.7 Pa or less to obtain a polyethylenenaphthalate composition having an intrinsic viscosity of 0.61. The alternating current volume resistivity value at 290 ° C. of this polyester was 3.1 × 10 ⁷ Ωm.

The obtained polyethylene naphthalate composition is formed into a film in the same manner as in Example 9 to obtain a polyethylene naphthalate film.

The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Example 11

In Example 9, the polyethylene and the like in the same manner as in Example 9 except that 100 parts of 2,6-naphthalenedicarboxylic acid dimethyl is 91 parts of 2,6-naphthalenedicarboxylic acid dimethyl and 9 parts of dimethyl isophthalic acid. A phthalate film is obtained. The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Examples 12-17

In Example 9, the amount of each of the 3,5-dicarboxybenzenesulfonic acid tetrabutylphosphonium salt, magnesium acetate, calcium acetate, trimethyl phosphate and antimony trioxide, the type and amount of the inert fine particles to be added, and the average particle diameter are shown in Table 3, Polyethylene naphthalate films are obtained in the same manner as in Example 9 except for the changes as shown in Tables 4 and 5. The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Examples 18 and 19

Polyethylene in Example 11 was changed in the same manner as in Example 11, except that acid components other than naphthalenedicarboxylic acid, the amount thereof, and the average particle diameter of the inert fine particles were changed as shown in Tables 3, 4, and 5 Obtain a naphthalate film. The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Example 20

In Example 9, a polyethylene naphthalate film is obtained in the same manner as in Example 9 except that the concentration of the spherical silica in the polymer is changed as shown in Tables 3, 4, and 5. The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Comparative Examples 5-7

In Example 9, each addition amount of 3, 5- dicarboxy benzene sulfonate tetrabutyl phosphonium salt, magnesium acetate, trimethyl phosphate, diethylene glycol, and antimony trioxide, the kind, average particle diameter, and addition amount of the inert fine particles added are shown in Table 3. , Polyethylene naphthalate film is obtained by the same method as Example 9 except having changed as shown in Table 4 and Table 5. The characteristics of this film are shown in Table 3, Table 4 and Table 5.

Sulfonate *: 3,5-dicarboxybenzenesulfonate tetrabutylphosphonium salt

Polymer composition Acid components other than naphthalenedicarboxylic acid Inert particulate Diethylene Glycol Content (wt%) Kinds Usage amount (mol%) Particle Type Average particle size (㎛) Content (wt%) Example 9 - - Spherical silica 0.06 0.05 0.7 Example 10 - - Spherical silica 0.06 0.05 1.0 Example 11 Isophthalic acid 10 Spherical silica 0.06 0.05 0.7 Example 12 - - Spherical silica 0.06 0.20 0.7 Example 13 - - Spherical silica 0.06 0.10 0.7 Example 14 - - Spherical silica 0.06 0.05 0.7 Example 15 - - Silica alumina 0.20 0.05 0.7 Example 16 - - Alumina 0.50 0.05 0.7 Example 17 - - Titania 0.50 0.05 0.7 Example 18 Isophthalic acid 5 Spherical silica 0.10 0.05 0.7 Example 19 Terephthalic acid 10 Spherical silica 0.10 0.05 0.7 Example 20 - - Spherical silica 0.06 3.00 0.7 Comparative Example 5 - - Spherical silica 3.00 0.05 0.7 Comparative Example 6 - - Spherical silica 3.00 0.10 0.7 Comparative Example 7 - - Spherical silica 3.00 11.00 0.3

Film evaluation Flatness Precipitated Particles (wt%) Dispersibility Electrostatic adhesion Film Production Stability Example 9 ◎ 0.01 or less ○ ○ ◎ Example 10 ◎ 0.01 or less ○ ○ ◎ Example 11 ◎ 0.01 or less ○ ○ ◎ Example 12 ◎ 0.01 or less ○ ○ ◎ Example 13 ○ 0.01 ○ ○ ◎ Example 14 ○ 0.01 ○ ○ ◎ Example 15 ○ 0.01 ○ ○ ◎ Example 16 ○ 0.01 ○ ○ ◎ Example 17 ○ 0.01 ○ ○ ◎ Example 18 ◎ 0.01 or less ○ ○ ◎ Example 19 ◎ 0.01 ○ ○ ◎ Example 20 ○ 0.01 or less △ ○ ◎ Comparative Example 5 × 0.02 ○ ○ ◎ Comparative Example 6 × 0.03 ○ ○ ◎ Comparative Example 7 ×× 0.03 × ○ ◎

As is apparent from the above results, the polyalkylene naphthalate of the present invention is excellent in electrostatic adhesiveness and high-speed winding property at the time of film formation, and the film obtained is uniform in thickness and excellent in surface flatness.

According to the present invention, polyalkylene naphthalate which is excellent in electrostatic adhesion and useful for forming a magnetic recording medium, especially a film for high density magnetic recording medium, can be produced with high efficiency.

Claims (28)

A polyalkylene naphthalate having a naphthalenedicarboxylic acid component as a main dicarboxylic acid component and an aliphatic glycol component as a main glycol component, wherein the polyalkylene naphthalate comprises (a) an antimony compound and (b) an ester-forming functional group. A polyalkylene naphthalate for film comprising sulfonic acid quaternary phosphonium salt compound units having a ratio satisfying the following formulas (1) and (2), respectively. 0 <Sb ≤80 (1) 0 <S / Sb ≤0.4 (2) (Wherein Sb and S are molar ratios of sulfonic acid quaternary phosphonium salt compound units each having an antimony compound and an ester-forming functional group per total dicarboxylic acid component forming a polyalkylene naphthalate (unit: mmol%)) Indicates.) The sulfonic acid quaternary phosphonium salt compound unit according to claim 1, wherein the sulfonic acid quaternary phosphonium salt compound unit having (a) an antimony compound and (b) an ester-forming functional group is contained in a ratio satisfying the following formulas (1 ') and (2') Polyalkylene naphthalate for films characterized by the above-mentioned. 5 <Sb ≤70 (1 ') 0.001 ≤ S / Sb ≤0.3 (2 ') (In the above formula, Sb and S have the same meaning as the definition in claim 1 above.) The polyalkylene naphthalate for film according to claim 1, wherein the polyalkylene naphthalate contains a magnesium compound, a calcium compound and a phosphorus compound in a proportion satisfying the following formulas (3), (4) and (5), respectively. 10 ≤ (Mg + Ca) ≤120 (3) 0.5 ≤Mg / Ca ≤10 (4) 0.5 ≤ (Mg + Ca) / P ≤ 10 (5) (In the above formula, Mg, Ca and P each contain a sulfonic acid quaternary phosphonium salt compound unit having a magnesium compound, a calcium compound and an ester-forming functional group per all dicarboxylic acid components forming a polyalkylene naphthalate). Molar ratio of the total phosphorus compound (unit is mmol%).) The polyalkylene naphthalate for film according to claim 1, wherein the polyalkylene naphthalate contains a magnesium compound, a calcium compound and a phosphorus compound in a ratio satisfying the following formulas (3 '), (4') and (5 '), respectively. Rennaphthalate. 20 ≤ (Mg + Ca) ≤ 110 (3 ') 0.5 ≤Mg / Ca ≤9 (4 ') 1 ≤ (Mg + Ca) / P ≤ 7 (5 ') (In said formula, Mg, Ca, and P have the same meaning as the definition in said 3rd term.) The polyalkylene naphthalate for film according to claim 1, wherein the aliphatic glycol component is at least one glycol component selected from the group consisting of an ethylene glycol component, a propylene glycol component, and a butylene glycol component. The polyalkylene naphthalate for film according to claim 1, wherein the polyalkylene naphthalate is polyethylene naphthalate. The polyalkylene naphthalate for film according to claim 1, wherein the polyalkylene naphthalate contains 20 mol% or less of terephthalic acid component and / or isophthalic acid component per total dicarboxylic acid component. 2. The polyalkylene naphthalate for film according to claim 1, wherein at least 80 mol% of the total repeating units of the polyalkylene naphthalate are ethylene-2,6-naphthalate units or ethylene-2,7-naphthalate units. The polyalkylene naphthalate for film according to claim 1, wherein the polyalkylene naphthalate contains 0.4 to 3% by weight of diethylene glycol units. A polyalkylene naphthalate having a naphthalenedicarboxylic acid component as a main dicarboxylic acid component and an aliphatic glycol component as a main glycol component, wherein the polyalkylene naphthalate is (a) an antimony compound and (b) an ester formability. The sulfonic acid quaternary phosphonium salt compound unit which has a functional group is contained in the ratio which satisfy | fills following formula (1) and (2), respectively, and also contains inert fine particles whose average particle diameter is 0.01-0.5 micrometer. Polyalkylene naphthalate composition. 0 <Sb ≤80 (1) 0 <S / Sb ≤0.4 (2) (Wherein Sb and S are molar ratios of sulfonic acid quaternary phosphonium salt compound units each having an antimony compound and an ester-forming functional group per total dicarboxylic acid component forming a polyalkylene naphthalate (unit: mmol%)) Indicates.) The polyalkylene naphthalate composition for film according to claim 10, wherein the inert fine particles are contained in an amount of 0.01 to 10 wt% based on the polyalkylene naphthalate. The polyalkylene naphthalate composition for film according to claim 10, wherein the inert fine particles are inorganic fine particles. The polyalkylene naphthalate composition for film according to claim 10, wherein the inert fine particles are silica particles, titania particles, or alumina particles. The polyalkylene naphthalate composition for film according to claim 10, wherein the inert fine particles are pore volumes of 1.0 ml / g or less, specific surface area of 100 m ² / g or less, and monodisperse spherical inorganic fine particles. The polyalkylene naphthalate composition for film according to claim 10, wherein the inert fine particles are monodisperse spherical silica fine particles. The film according to claim 10, which contains (a) an antimony compound and (b) a sulfonic acid quaternary phosphonium salt compound unit having an ester-forming functional group, in a ratio satisfying the following formulas (1 ') and (2'), respectively. Polyalkylene naphthalate composition. 5 <Sb ≤70 (1 ') 0.001 <S / Sb ≤0.3 (2 ') (In said formula, Sb and S have the same meaning as the definition in said 10th term.) The polyalkylene naphthalate composition for film according to claim 10, wherein the polyalkylene naphthalate contains a magnesium compound, a calcium compound and a phosphorus compound at a ratio satisfying the following formulas (3), (4) and (5), respectively. . 10 ≤ (Mg + Ca) ≤120 (3) 0.5 ≤Mg / Ca ≤10 (4) 0.5 ≤ (Mg + Ca) / P ≤ 10 (5) (In the above formula, Mg, Ca and P each contain a sulfonic acid quaternary phosphonium salt compound unit having a magnesium compound, a calcium compound and an ester-forming functional group per all dicarboxylic acid components forming a polyalkylene naphthalate). Molar ratio of the total phosphorus compound (unit is mmol%).) 11. The polyalkylene naphthalate according to claim 10, wherein the polyalkylene naphthalate contains a magnesium compound, a calcium compound and a phosphorus compound at a ratio satisfying the following formulas (3 '), (4') and (5 '), respectively: Lennaphthalate composition. 20 ≤ (Mg + Ca) ≤ 110 (3 ') 0.5 ≤Mg / Ca ≤9 (4 ') 1 ≤ (Mg + Ca) / P ≤ 7 (5 ') (In said formula, Mg, Ca, and P have the same meaning as the definition in said 17th term.) The polyalkylene naphthalate composition for film according to claim 10, wherein the aliphatic glycol component is at least one glycol component selected from the group consisting of an ethylene glycol component, a propylene glycol component and a butylene glycol component. The polyalkylene naphthalate composition for films according to claim 10, wherein the polyalkylene naphthalate is polyethylene naphthalate. The polyalkylene naphthalate composition for film according to claim 10, wherein the polyalkylene naphthalate contains 20 mol% or less of terephthalic acid component and / or isophthalic acid component per total dicarboxylic acid component. The polyalkylene naphthalate composition for film according to claim 10, wherein the polyalkylene naphthalate is at least 80 mol% of all the repeating units are ethylene-2,6-naphthalate units or ethylene-2,7-naphthalate units. The polyalkylene naphthalate composition for film according to claim 10, wherein the polyalkylene naphthalate contains 0.4 to 3% by weight of diethylene glycol units. In the manufacturing method of the polyalkylene naphthalate which makes naphthalene dicarboxylic acid the main dicarboxylic acid, ester ester derivative thereof, and the glycol which uses aliphatic glycol as a main glycol, transesterifies, and then polycondenses it, Before the start of the polycondensation reaction, (a) an antimony compound and (b) a sulfonic acid quaternary phosphonium salt compound having an ester-forming functional group is added. . The biaxially oriented film formed of the polyalkylene naphthalate of Claim 1. The biaxially oriented film formed from the polyalkylene naphthalate composition of Claim 10. A high density magnetic recording medium comprising a biaxially oriented film formed of the polyalkylene naphthalate according to claim 1 as a base film. A high density magnetic recording medium comprising a biaxially oriented film formed of the polyalkylene naphthalate composition according to claim 10 as a base film.